It is known that a bicycle handlebar assembly normally comprises a handlebar attachment (also called stem), a handlebar rod and an attachment stop, which fasten together the handlebar rod with the handlebar attachment.
The handlebar attachment is mounted on the top of the fork, fixedly connected to it, and faces forwards, horizontal in the direction of forward movement of the bicycle or almost horizontal, in a direction tilted upwards or downwards by a few degrees with respect to the direction of forward movement of the bicycle.
In the field of racing bicycles, there is also a well-known need to reduce the weight of each component, both by using light materials (such as light metals and composite materials) and by taking great care in sizing each detail, so as to reduce the thicknesses and sizes whilst still ensuring the necessary mechanical strength.
Moreover, particularly for bicycles intended for races, there is an ever-increasing need for careful aerodynamic profiling, particularly of the bicycle-cyclist assembly, so as to reduce the resistance offered by air during high-speed travel. A great deal of attention has therefore been placed on the wheels (with the development of lenticular wheels) and on the cyclist's clothing. Moreover, more recently particular attention has been given to the components that determine or in any case influence the position taken up by the cyclist's body, like the position and shape of the saddle, of the handgrips on the handlebars and of the gear and brake levers. On the other hand, no great attention has yet been paid to the aerodynamic characteristics of each component of the bicycle. In particular, handlebar assemblies have not yet been the subject of much attention in terms of aerodynamics, apart from—as stated—in relation to the position of the cyclist.